1. Field of the Invention
The present invention relates to a method and an apparatus for packaging a number of substantially cylindrical packages consisting of a within certain limits elastic insulation material, for instance mineral wool, said packages having open ends, but being at their side faces surrounded by a substantially airtight foil layer, by which method the open ends of the packages are temporarily closed in an essentially airtight way, the volume encased by the foil layer and the temporary sealings being connected to a vacuum source to reduce the volume of the packages, the packages thus reduced being enclosed in a tight enclosure before the vacuum is disconnected.
2. Description of Related Art
A method of this kind has been disclosed in the U.S. Pat. No. 3,458,966. According to this known method a single roll of insulation material is placed in an airtight plastic bag, the bag being then evacuated, and, as a consequence, the insulation material is compressed by the surrounding air, until the volume has been reduced to such an extent that the bag with the insulation material may be placed in a sleeve with open ends, said sleeve having a diameter somewhat smaller than the original diameter of the roll. When the vaccum is suspended, the insulation material will try to regain its original volume, but is prevented therefrom by the sleeve. If the insulation material is provided with a covering of an essentially airtight material forming an outer side of the coil during the rolling, said covering may be used as a kind of enclosure with open ends, the package only having to be closed at the ends at the evacuation. For this purpose a cap is proposed. According to this known method only individual packaging of the cylindrical packages is disclosed, said packages retaining also after their insertion in the sleeve their cylindrical shape. The cylindrical shape is not advantageous for a later putting together of the packages on pallets, and the individual enclosing of each package in a separate enclosure is considerably material consuming.
In the patent it is ascertained that the compression of the insulation material by means of vacuum is more advantageous than other types of compression, as the degree of compression, which is tolerable without loosing the capability of the insulation material of regaining its original form, is higher by compression by means of vacuum than by means of other mechanical means. The idea of the invention is to use this gentle compression in a special way in order to obtain the maximum use of a given transport volume.